<?php
/**
 * Created by PhpStorm.
 * User: YUWENXUAN
 * Date: 2017/4/1
 * Time: 15:32
 */

$arr = ['foo'=>'bar',12=>true];
foreach ($arr as &$value){
    if(is_string($value)){
        $value.='--string';
    }
}

//print_r($arr);

print_r([
    'a',
    'b',
    'c'
]);